If it makes you feel better, many people get signed up for Medicare Part A whether they like it or not, because they signed up for Social Security (The SSA will automatically sign you up for Part A in this case). You can't avoid it once you sign up for Social Security.
To quote the SSA: "If you are age 65 or older and receive Social Security benefits, you will be automatically enrolled in Part A."
As for why your tax did not appear to change, this is a bit complicated.
When your W-2 is entered, the code W amount in box 12 are HSA contributions made through your employer. Before the W-2 is printed, the code W amount is removed from Wages in boxes 1, 3, and 5 (this is how this type of HSA contribution is a benefit, because it was never in your income in the first place).
However, the IRS does not consider these contributions to be valid until you demonstrate that you have the appropriate HDHP insurance. So as soon as your W-2 is entered, the code W amount is added back to your Wages, pending you showing proper insurance coverage in the HSA interview. You don't see this, unless you are watching the Refund Meter very closely (which I discourage).
If you show proper HDHP coverage in the HSA interview, then the code W amount will be removed from Wages, putting Wages back to where they were on your W-2. But in your case, all or part of your code W amount was disallowed, so they were added back to income, which is where they were when you first entered the W-2.
Of course, I cannot see your return, but I hope this will help explain why you see what you see.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
